The Planetary Society was not only started by Dr. Sagan, but it is also a great resource of information on him and the World’s largest Space-interest group.
Also, as it is the holiday season, why not make a donation to SETI in commemoration of Dr. Sagan in a loved one’s name? They are always desperate for funding, and it could make a nice gift to the science enthusiast in your circle.
Are you a Space enthusiast with lots of idle disk space you don’t use, and are hard up for cash to make a donation? Well here’s an alternative to a donation that’s just as good if not better: download the BOINC client program and give a portion of your disk to research sciences. There’s a few to choose from and SETI is one of them.